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U320 SCSI DISKS IN A U160 ENCLOSURE


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#1 chipstone

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Posted 11 November 2004 - 07:46 PM

I need information from SCSI gurus on the following question:

I’ve seen external SCSI enclosures for a good price, in black, most of the U320 are ugly, but they are rated and advertised as Ultra 160. I have 4 SCA-2 disks rated at U 320, and so is my HBA, to be used for external connection: LSI 22320 SCSI card.

If I install the U320 SCA-2 disks into the U160 enclosure, will the drives interface only at U160 with the U320 HBA card?, or will they interface at U320?

I am unable to find information, and would like to know of any experience before purchasing the unit.

I don’t understand, if the U320 & U160 enclosures use the same internal 80 pin connector & external 68 pin connectors, why the difference. I think the speed is controlled by the drives and the HBA SCSI card, right?

Or is their something inherent to U320 cables & storage enclosures not found on the U160 counterpart.

Any input would be appreciated.

#2 MaxBurn

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Posted 11 November 2004 - 08:04 PM

Probably will introduce a certain amount of noise if it works at all at 320. I wouldn't want to depend on it.

#3 chipstone

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Posted 11 November 2004 - 08:20 PM

Thank you for your response, but:

My suspicion is that they are compatible, this is the reasoning behind my argument, maybe is referential reasoning:

I while back I purchased a Trimm Technologies Fibre Drive Enclosure; the enclosure was designed to work at with U160 FC drives rated at 200MB/sec, and with 1/GB HBA FC interface cards.

I installed 4 ST373453FC U320 drives into the enclosure; 40-pin interface backplane, then attached the fibre-optics cables, FC-AL loop, back to the Emulex 2/GB HBA FC card, and my sustained speeds are consistent with 2/GB FC interface.

So the enclosure, manufactured before the 2/GB HBA technology was implemented did not prevent the drives from operating at optimal 2/GB interface.

#4 continuum

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Posted 11 November 2004 - 09:12 PM

It'll probably work just fine, but unless you're stuffing enough drives in the enclosure to stretch Ultra160's limitations, I doubt you'll be able to tell the difference...?

#5 chipstone

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Posted 11 November 2004 - 10:34 PM

Thanks for the info.

I am only installing 4 SCA-2 drives: 2 – 146GB and 2 73GB. They currently reside inside the PC, using a 80-68 pin converter, but I’ve been reading that the use of the converter can put a strain on the SCSI channel attached with regular 68 Pin drives and SCA-2 converter to 68 pin interface.

#6 Chew

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Posted 11 November 2004 - 10:42 PM

U320 and U160 are essentially the same other than an 80MHz clock rate for U320 and 40MHz for U160. A backplane is not a 'device' as such, in that it doesn't affect the usable SCSI mode. However, the quality of the components are rated and tested at a particular speed. This means that while there's no hard limits imposed by an U160 enclosure to prevent U320 operation, it's not tested therefore guaranteed. One would expect most hardware to be manufactured with plenty of margin, so most likely most U160 enclosures should work find at U320 speeds.

#7 sechs

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Posted 12 November 2004 - 12:10 AM

This is like the difference between USB and USB2 cables. As Chew says, it's simply a matter of rating of the hardware.

#8 chipstone

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Posted 12 November 2004 - 09:42 AM

Thanks for all the information provided.

The enclosure is made by StorCase. I will post a follow-up once it’s up and running.



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